Q: I’m going to run 220 to my garage, two wires will be hot and a neutral, I’m going to run the outlets using one hot side and a neutral and the lights using the other hot wire and a neutral, at the 220 outlet i will have two hots, will the third wire be a neutral or ground?

A: You can’t do this! This is a National Electrical Code (NEC) violation and extremely unsafe. The circuit breaker will not protect your 120 volt circuits and someone will get seriously injured.

To do this properly, I recommend installing a sub-panel in your garage. I would feed your sub-panel with either 50 amps or 100 amps of power. You need to install 2 – hots, 1 – neutral and 1 – ground. Grounding is extremely important and a major factor to allow your circuit breakers to trip during a fault.

If you do not wish to install a sub-panel in your garage, I recommend installing 3 circuits. One circuit for your 120 volt receptacles and one circuit for your lighting. In this application, I would install a 12/3 NMB with ground. With this cable, you will share the neutral so you need to ensure your 2 - 120 volt circuits are on separate phases in your breaker box. The best way to do this is install your new circuit breakers one above another on the same side of your breaker box. You also need to install a GFCI receptacle at your first receptacle location to protect all receptacles in your garage.

The third circuit is for your 220 volt receptacle. The size of this cable depends on what you are going to power up with it. Most welders, compressors and 220 volt A/C units do not need a neutral. This means you may run 2 – hots and 1 – ground. However, you need to check the specifications for the unit you are going to power up with your 220 volt receptacle.

You wire size depends on the amperage and distance from the breaker box. If your cable length is 125 feet or less you need 10 AWG for 30 amps, 8 AWG for 40 amps and 6 AWG for 50 amps. The rule of thumb is to increase your wire by 1 size for every 100 feet of length after the initial 125 feet.

Before you begin, be sure the power is off to the circuit you are working on and double check with a volt-meter. You also need to check with your local building codes department to ensure you may do your own electrical wiring. Some areas do not allow homeowners to install their own electrical wiring and you may need to hire a licensed or qualified electrician.

We sell a great book for homeowners and “do-it-yourselfers” that wish to do their own electrical wiring but, do not know much about electricity. The book is Wiring Simplified – 41st Edition and it is based on the 2005 National Electrical Code (NEC).

If the above information I have given does not work for your situation or you need further clarification, feel free to post your questions in the comment section.

Comments

i am going to use a sub panel in the garage using a 4wire cable
two hot a neutral and a ground,what size wire can i use,the air conditioner would be the biggest amp draw,would i tie in at the box on the outside of the house where it comes in at the 100 amp fuses?

Administrator on
January 19th, 2007 3:45 am

I need to know the amperage rating of your A/C unit to tell you the minimum size wire that you need. If it were me, I would install a 100 amp sub-panel. This would give you room for future growth without needing to upgrade.

For 100 amps, the wire size depends on how you are going to get from your breaker box in your house to your new sub-panel.

If you are going to install it in conduit, your need either # 4 THHN copper or # 2 XHHW aluminum.

If you are able to run a cable indoors, you need # 1 for copper or aluminum.

If you are going to run a wire overhead you need either # 4 copper or # 2 aluminum. Running overhead does not include a ground, so you need to install an 8′ x 5/8″ ground rod and install a # 6 bare copper wire between the ground rod and the ground bar in your new sub-panel.

In your new sub-panel, you need to ensure your grounds and neutrals are separated. Sometimes you need to remove a green screw from the neutral bar and othertimes there is a bonding strap between the neutral bar and the panel’s frame.

Installing electrical panels and sub-panels is tricky. This is one of the most important parts of your electrical system and it needs to be done right. I recommend hiring a licensed or qualified electrician to do this work.

You also need to check with your local building codes department to ensure you are able to do this work. In some areas, homeowners are not permitted to do their own electrical work. When you are finished, I highly recommend getting an inspection to ensure everything is correct and safe.

Be sure to turn off the power to what ever you are working before you begin any work and double check that it is off with a volt-meter.

larry smith on
January 19th, 2007 1:30 pm

im going to use flexable pvc,will 3/4 be big enough for #4 this will be underground?

Administrator on
January 20th, 2007 4:58 pm

I’m not sure what you are referring to with flexible PVC. If you mean the blue flexible conduit also known as Electrical Non-Metallic Tubing (ENT) or “smurf tube”, this will not work.

You need either schedule 40 or schedule 80 PVC. Schedule 80 needs to be installed from 18″ below grade to 8′ above grade. Your conduit needs to be buried 18″ deep minimum. The conduit size needs to be 1 1/4″.

While I believe you are a smart guy, your questions lead me to believe that you are very inexperienced with electricity. I can’t stress enough the importance of safety. Two worst case scenarios with electricity are electrocution and fire. I HIGHLY recommend getting an electrical inspection when the work is complete. You also need to be sure all power is off while you are working on your new circuit and double check several times with a volt-meter before touching any wires or breaker boxes.

Good luck and be safe!

Paul on
November 22nd, 2008 4:37 pm

I have a warehouse, and the past tenant went bankrupt – he had a box company and the motors were 220 receptacles hanging ever where , is there a way to split the 220 wires most have 4 wires in them – some have 3 and the ends of the receptacles have curve slots at the receptacle ,,,
am I able to make them general outlets 110/120. I am not sure what the right words are but I like to rewire them to break them down to general receptacles, to plug in 110/120 things lamps – and tv, all that stuff , i have bands that what to rent – but i needto run lots of wires .
the warehouse is wired every where with these 220 plugs and some have the 4 wires are exposed where they cut off the motors –most are 2 white and 2 black – any help would be appreciated , thank you Paul

George Mayer on
April 8th, 2009 4:20 pm

I did away with a hot tub but would like to use the existing wiring. The tun was 220 and my current need is to convert it to 110. Can that be done easily?

elena on
July 27th, 2010 2:06 pm

I’m going to install a 125 amps subpanel box to the garage from 200amps main box what size of electric wire do I need or what type ?
Elena

John on
March 21st, 2011 7:50 am

I have a 110/220 volt compressor that I’m currently running(on 220v) off a 220v dryer receptacle on a small porch.
I need to move this thing to my garage that is 60-70 feet from the electrical source.
Can I just connect to that dryer power source(with a proper junction box), and run the wire to my garage in conduit?and if so what size wire would I need?
The breaker box is in my basement and the dryer is a 30amp breaker.My service is 100amp.I’d like to be able to leave the wiring and breaker the way it is and just run it to a 220 dryer receptacle inside the garage.
The only use it would get is for the compressor.

Would there be a better or less costly way to go about this?

Any help is greatly appreciated

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